The handlebars and steering posts of bicycles must be made rugged for the reason that bicycle riders customarily exert a tremendous force thereon while pedaling in order to increase the cranking force imparted by their legs and feet into the main drive sprocket thereof. This force exerted into the handlebars represents wasted energy and it would be desirable to utilize this energy by employment of a crank system connected to chain drive the front wheel thereby achieving extra propulsion for the bicycle while requiring little or no additional effort on the part of the rider.
Others have proposed utilizing this wasted energy by pivotally connecting the handlebars to the steering system, thereby utilizing the pivotal motion to drive the front wheel of the bicycle.
The conversion of pivotal motion into rotational motion can be achieved by employment of a drive sprocket which is cranked by a connecting rod affixed to the handlebars, with the drive sprocket moving an endless chain connected to a driven sprocket affixed to the front wheel.
In the before described system, it is desirable to provide the driven sprocket with a one way or free-wheeling clutch assembly, thereby enabling the rider to discontinue and commence pivotal motion of the handlebars at any given time. This desirable feature, however, presents the problem of the crank and connecting rod failing to go over-the-center at the two dead-center positions of rotation, as well as sometimes causing crank reversal at each extreme length of travel of the connecting rod. Either of these situations is dangerous for the reason that when the crank is rotating to propel the bicycle in a forward direction, considerable resistance is encountered, according to the speed and power requirements of the bicycle, while hardly any resistance at all is encountered should the direction of rotation of the sprocket suddenly be reversed. Accordingly, while propelling a front wheel drive bicycle, should the crank reverse itself at either extreme limit of travel, the sudden removal of this resisting force can easily topple one from the bicycle causing potential injury to result. Therefore, it is desirable to have made available a biasing force which is placed on the connecting rod in such a manner that the rod is always biased at each extreme length of travel thereof to cause the crank to continue to turn in the appropriate direction to propel the bicycle in a forward direction.